Quick question about CAPL (passing a message as an argument to a function)

[pk_volt]

I found a pretty helpful CAPL programming tutorial pdf on here, which has helped me get started with CAPL very quickly.

However, I'm trying to pass a message to another function as an argument, and I can't seem to get this right. I'm basically just trying to do a simple loopback from CAN1 to CAN2. Note: the commented out code in "on message CAN1.vtmCmd1" loopback code works, but I would preferably like to use functions to organize my test cases.


Here is my code.

on message CAN1.vtmCmd1
{
 
    //Loopback for 1 second, fault for 600ms.
    invalid_test_0x232(this);
  /*  message *gatewayMsg;
    gatewayMsg = this;
    gatewayMsg.CAN = 2;
    output(gatewayMsg);
    */
}

void invalid_test_0x232(message vtmCmd1 tmCmd1){
    int tm;
    char test_state = 0;
    char alive_counter;

    //configure pkt to loop out to CAN2
    tmCmd1.CAN = 2;
   
    output(tmCmd1);

---------- Post added at 20:00 ---------- Previous post was at 19:56 ----------

ah, I just figured it out. Turns out you have to create a "pointer" or another instance for the gateway message inside my function: For future references, here is the code that i got it to work:

void invalid_test_0x232(message vtmCmd1 tmCmd1){
    int tm;
    char test_state = 0;
    char alive_counter;

    //configure pkt to loop out to CAN2
    //tmCmd1.CAN = 2;
    //output(tmCmd1); 
 
     message *gMsg;
     gMsg = tmCmd1;
     gMsg.CAN = 2;
     output(gMsg);
 /*
}

 

[EmilN]

On a similar note, how can I return a message from a function? I have tried to declare my function as:

message MyFunction(message * msg)
{
   return msg;
}

but this gives a parse error on the return type (i.e. message).

 

[pk_volt]

On a similar note, how can I return a message from a function? I have tried to declare my function as:

message MyFunction(message * msg)
{
   return msg;
}

but this gives a parse error on the return type (i.e. message).

Hi there, I, too was unable to find out a way on how to return a message, but I did find a discovery that might help solve your problem.

I noticed that if you pass a specific message to a function, it seems to retrieve it as a pointer, allowing you to modify its contents without having to return it.

For example, this is a simple test I did. note that I am sending a constant value of 1 for my gear_cmd from my CAN device connected to my Cancase logger

on message CAN1.vtmCmd1
{
    write("Gear Command before: %d", this.gear_cmd);

    testfunc(this);
    write("Gear Command now: %d", this.gear_cmd);
}

void testfunc (message vtmCmd1 msg)
{

msg.gear_cmd = 3;

}

and the output:
CAPL Gear Command now: 3
CAPL Gear Command before: 1
CAPL Gear Command now: 3
CAPL Gear Command before: 1
CAPL Gear Command now: 3
CAPL Gear Command before: 1
CAPL Gear Command now: 3
....



Let me know if this helps.

 

[EmilN]

Thank you very much! I had a though that this might be the case, but I have not yet had the possibility to try it out, but I will try to do that now. Thanks for your help!

 

[pk_volt]

another quick question.

How do you use "Value Table" parameters in CAPL scripts. For example, if I have a message signal pwr_state associated with a value table with values {ON, OFF, ERROR}

how do I do something like: message.pwr_state = ON;

or something like that?

 

[EmilN]

Can you use enum?

    enum State {isOn, isOff, isError};
    enum State state;
    state = (enum State) isOn;

    switch (state) {
     case isOn:
        write("It is on.");
        break;
     case isOff:
        write("It is off.");
        break;
     case isError:
        write("There is an error.");
        break;
    }

    if (state == isOn)
        write("OK");

 

[pk_volt]

Can you use enum?

    enum State {isOn, isOff, isError};
    enum State state;
    state = (enum State) isOn;

    switch (state) {
     case isOn:
        write("It is on.");
        break;
     case isOff:
        write("It is off.");
        break;
     case isError:
        write("There is an error.");
        break;
    }

    if (state == isOn)
        write("OK");

Did that code actually work? I'll have to give it a try tomorrow. Last time I looked at the programming reference, CAPL doesn't support enums. Nevertheless, I think it is still more convenient to grab values strait from the value table into CAPL scripts

 

[EmilN]

I have to say that I never tried it, but it does compile and enums are supported in CAPL according to the help file. (I'm using CANalyzer 7.2 if that matters.)